The present invention relates to an internal combustion engine that directly injects gasoline into a combustion chamber (which is equivalent in meaning to a cylinder) for combustion, namely a direct injection type gasoline engine. More specifically, it relates to an improvement made on an internal combustion engine of this type involving homogeneous combustion.
Japanese Patent Laid-open No. Hei 9-280138 discloses a direct injection type gasoline engine in which, in a technique as the prior art, a mixture of EGR gas and fuel (gasoline) is formed outside a combustion chamber and is then directly injected into the combustion chamber. A technique as an invention is also described in the publication, in which a mixture of compressed air and fuel (gasoline) is formed outside the combustion chamber and is directly supplied into the combustion chamber.
Japanese Patent Laid-open No. 2000-97032 describes a direct injection type gasoline engine in which while air and EGR gas are mixed and the mixture is supplied into a combustion chamber, fuel (gasoline) is directly injected into the combustion chamber for combustion.
[Patent Literature 1]
Japanese Patent Laid-open No. Hei 9-280138
[Patent Literature 2]
Japanese Patent Laid-open No. 2000-97032
According to these prior art techniques, the EGR gas is mixed with fresh air or fuel outside the combustion chamber before the resultant mixture is supplied to the combustion chamber. Because of this arrangement, the amount of EGR gas to be introduced into the combustion chamber is restricted in a variety of ways, being limited to a relatively small amount.
If the amount of EGR gas is made large, on the other hand, the distribution of rich-to-lean air-fuel mixture ratios in the combustion chamber exhibits no reproducibility, resulting in unstable combustion performance.